The major objective of this program of research is to provide basic information concerning the host response to tumor antigens and the possibility of chemical modification of such antigens to obtain a more efficient immune response to the corresponding tumor cell. The specific goal of this work is the optimization of the myeloma-specific immunity generated against the murine plasmacytoma, MOPC-315, by immunization with specific myeloma protein. The research will proceed in two stages: 1) the analysis of the cellular effectors responsible for the immunity, by adoptive transfer experiments. This involves the transfer of specifically immune cells or fractionated cell suspensions to unimmunized recipients, with subsequent challenge of the recipients with tumor cells. 2) the chemical modification of the specific myeloma protein-315, which is associated with the tumor as a cell surface antigen as well as circulating paraprotein. Attempts will be made to prepare a modified antigen which favors the elicitation of a strong, predominantly cellular response. Exploitation of this system can provide important information basic to a rational immunotherapy of human cancer.